Processes for encapsulating oils and oil soluble substances are well known in the art.
U.S. Pat. No. 4,389,419, for example, which is incorporated herein by reference, relates to a process for encapsulating oils and oil-soluble substances in multi-compartmentalized, mechanically stable microcapsules. The process comprises the steps of first forming an emulsion consisting of a continuous phase comprising an aqueous solution of an alkali metal alginate and optionally a water-soluble, alcohol-insoluble filler such as a polysaccharide, and a dispersed phase of an oleophilic substance such as one or more vitamins dissolved in an oil. The emulsion is then formed into droplets which are thereafter immersed in an alcoholic solution of multivalent cations, to produce a shape-retaining alginate matrix filled with precipitated polysaccharide and enclosing plural oil droplets. The vitamins are thereby protected from oxidative degradation and can be handled like conventional crystalline solids.
Algin is a polysaccharide found in brown algae. Alginates and their derivatives have become significantly important hydrocolloids and are applied in a wide variety of industrial fields.
Algin is a polysaccharide that contains β-(1→4)-D-mannuroic acid of structure I: and α-(1→4)-L-guluronic acid of the structure II: 
Algin is a heterogeneous polymer consisting of the following three types of molecular blocks:    i) M-block, consisting of only M—M linking;    ii) G-block, consisting of only G—G linking; and    iii) Random block, M and G randomly linked.
Calcium alginate gel beads are used to entrap a wide variety of substances. The entrapment with calcium alginate is particularly favored because of the mild conditions employed add the nontoxicity of the reactants. Typically, the procedure simply involves dropping a 1-2% solution of sodium alginate into a 1-2% solution of calcium chloride. The alginate solution may be pumped through a small orifice, such as a needle, or rotating plate or vibrating droplets feeder and allowed to free-fall, producing a spherical bead, which gels upon contact with the calcium source. The beads then remain in the calcium bath until hardened.
Islets of Langerhans, the cells producing the insulin in the pancreas, may be entrapped in an alginate polycation microcapsule to allow small molecules such as glucose and other nutrients to diffuse freely, while preventing the passage of large molecules and cells. Physico-chemical properties of the microcapsules, such as shape, size and permeability, can be controlled (Goosen et al., Applied Biotechnology and Bioengineering, 10, 87-98, 1984).
According to U.S. Pat. No. 4,389,419, “. . . the amount of oil used may range broadly between 1% and close to 30%. However, at the higher end of the range, the stability of the oil-in-water emulsion is decreased, and the quality of the microcapsule is reduced.” (column 3 lies 5-9).
BASF Health and Nutrition publication dated October 1997 reports a process for microencapsulation using gelatin. In this report, the mean particle size of the final product is approx. 250μ and the concentration of the active ingredient is up to 50%. However, the BASF process involves the use of gelatin, which is an undesirable limitation. Gelatin is purified mainly from pigs and cows which are susceptible to The Mad Cow disease and the Foot and Mouth disease.
U.S. Pat. No. 6,146,671 discloses a method for protecting a heat and/or oxygen-labile compound by encapsulation in a protective matrix of alginate and an additional polymeric material, which provides a single layer coating system. U.S. Pat. No. 6,146,671 further suggests the use of gelatin as a preferred protective polymer. Recently, the market is looking for materials which are not derived from animals which are susceptible to Mad Cow Disease.
In view of the above, the need for a stable, GMO-free, vegetable source alginate microcapsule having a high lipophilic compound content, small particle size with improved bioavailability, remains.
It is therefore the objective of the present invention to provide a microencapsulated formulation of lipophilic compounds which contains a relatively high lipophilic compound content with improved bioavailability and stability.